1. Field of the Invention
The present invention relates to a nose gear installation and more particularly to a means for securing an aircraft nose landing gear assembly into the nose wheel well support structure of an aircraft.
2. Background Information
Prior Art Literature
U.S. Pat. No. 5,337,976 to Derrien issued Aug. 16, 1994 which shows a dual purpose shock absorber/actuator including the feature of having a second stage that helps diminish the impact of a crash landing, the system being primarily directed toward rotorcraft which encounter these conditions during autorotation landings.
Prior Nose Gear Systems
As can be seen in FIG. 1, in prior commercial transport aircraft, the nose landing gear 12 generally consists of a shock strut assembly 10 and drag brace members 20. The shock strut carries the wheels (not shown) and steering mechanism (not shown) and pivots about trunnion pins 30. Bushings 40 located in the side walls of the nose wheel well receive and support the trunnion pins 30. The drag brace members 20 are used to unfold the landing gear and lock it in place when brace members 20 also brace the landing gear against forward and aft loads. The drag brace members 20 are secured to the nose wheel well support structure in a way substantially the same as the way in which the shock strut assembly 10 is secured to support structure.
Problems of the Prior Nose Gear Systems
The previous way of securing the nose landing gear assembly 12 to the nose wheel well structure is as shown in FIG. 2, the old method employs joints at each of the landing gear support fittings 45 having a spherically mounted self lubricating bearing 50, a cylindrical steel pin 60, and a corresponding cylindrical bushing 70 in the landing gear assembly 12. Also at each joint location, a retaining nut, lock wire and washers (not shown in FIG. 2) are secured to the steel pin on the outboard (pressurized) side of the nose wheel well structure.
It is very difficult for a production worker or mechanic to access the outboard side of the nose wheel well at each of the joint locations and install retaining nuts, washers and lockwires. Consequently, the initial installation and subsequent removal and replacement of nose landing gear assemblies is a difficult and time consuming operation requiring considerable skill and effort. Accordingly, there is a need for an improved nose landing gear trunnion pin joint for installation of landing gear assemblies into the nose wheel well that does not require outboard retaining nuts, washers, or lockwires. Such a landing gear assembly would be designed so that a mechanic could install, remove or replace the nose landing assembly without accessing the outboard side of the nose wheel well.
A further nose landing gear trunnion pin arrangement relies on outboard side installed retaining nuts and the like as described above. Such aircraft, however, use trunnion pins that install only from the inboard side. However, the landing gear support fittings in the nose wheel well are single piece fittings designed to a safe life requirement. Such aircraft use two-sided fittings that are designed to a fail safety requirement. These two-sided fittings require an inboard bushing and an outboard bushing and so, because an unrestrained outboard bushing could migrate outboard, trunnion pins were supplied with outboard retaining nuts.